Some modern communications solutions are based on VoIP (Voice-over IP (Internet Protocol)) technology, which is the transmission of calls over a data network based on the IP. The communication is in the form of packet data and thus there is no fixed connection as there would be in the case of switched networks. The communication can be text, voice, graphics or video. In order to simplify IP communication problems, standards have been developed and adopted in the industry. Examples of such standards are H.323 (Packet based communication systems) and SIP (Session Initiation Protocol). These standards are followed when designing new hardware and software. The SIP standard covers the technical requirements to set-up, modify and tear down multimedia sessions over the Internet. A multimedia communication session between two endpoints will be referred to as a call.
Communication solutions, whether they be switch based or packet based, are defined and designed for a specific number of users and call processing capacity, generally defined by the number of ports (telephone terminations), and the amount of processing available on a central processing equipment that provides routing and call processing functionality. Hence, equipment vendors generally develop and market versions of the same product for different customer size and needs. However, a customer needs to upgrade to larger central processing equipment once the number of ports required and/or call-processing requirements exceed the capacity of the central processing equipment.
Current multimedia communication systems use a central processing equipment and simple user terminal sets. These simple user terminal sets are referred to as “stimulus terminals” as they simply send user stimuli such as key presses to the central processing equipment. In large systems, the central processing equipment is generally a very powerful computer controlling a number of functions on circuit boards called line cards, which connect telephone sets to the computer. The central processing equipment receives hook-switch information and key presses known in the art as DTMF (Dual Tone Multi-Frequency) tones from the telephone sets, and provides feedback to the telephone sets for example by sending a dial-tone or a ringing tone to the telephone sets. By interpreting the key presses, the central processing equipment controls the interconnection of the telephone sets based on numbers dialed by the telephone sets.
Call transfer has been provided as part of the central call processing equipment. There are two types of call transfers namely, blind or consultative transfers. To perform a blind transfer while on a call, a user presses a transfer key or presses the switchhook momentarily. The central call processing equipment places the call on hold and a special dial tone is provided to the user to dial a new destination number. Once the user hears a ringing tone he or she may hang up to complete the transfer. To perform a consultative transfer while on a call a user presses a transfer key or depresses the switchhook momentarily. The central call processing engine places the call on hold and a new dial tone is provided to the user to dial the destination number. Once the destination party answers the user may consult with the destination. The user hangs up to complete the transfer. In both blind and consultative transfers, it is the central call processing engine that places a call on hold and establishes a media path with a new destination. Such a system is not well suited for scalability. In addition, centralized equipment adds costs to the total cost of the communication solution.